Mastering email security: A practical guide to security and compliance
1 April 2025
0 min read
Introduction: What is email security?
Email security is a set of practices, protocols, and tools designed to protect email communications from cyber threats and unauthorized access.
It involves securing the content, sender, and recipient of email messages, as well as ensuring the integrity of email systems and their networks. Email security also protects users from various types of email-based attacks, such as phishing, malware, and spam.
By the end of this guide, you'll get:
➔ A clear understanding of what email security is and current email security threats.
➔ An overview of key email security measures, like authentication protocols, encryption, and secure email gateways.
➔ A guide to compliance with industry regulations like GDPR, HIPAA, and CCPA.
➔ Practical steps for assessing email security, and a breakdown of email security best practices.
➔ Recommendations on email security software and tools, including Exclaimer for secure email signature management.
The importance of email security today
Email is the top communication tool in businesses. However, it’s also one of the primary methods that hackers use to target organizations. In fact, it’s estimated that up to 80% of cyberattacks are from phishing.
Bad actors increasingly use email to exploit vulnerabilities like weak authentication or unsecured email signatures. This makes email security critical for protecting sensitive information, maintaining trust, and complying with regulatory standards. Poor email security can lead to data breaches, financial loss, and reputational damage for organizations.
With the increase in remote work, cloud-based communication, and AI-driven technologies, email security has never been more important. All businesses must adopt advanced security measures so their email systems are constantly protected from evolving threats. This is especially the case as compliance requirements (like GDPR) require tighter data protection practices.
The current landscape of email security
With so many current and emerging threats across digital communications, it’s on IT professionals to prioritize continuous monitoring, carry out regular system updates, and educate employees.
Here are just some of the rising threats facing email security today:
The rise of AI
As artificial intelligence (AI) continues to advance, it will play an increasingly significant role in email security. While AI offers new capabilities to combat cyber threats—such as identifying phishing attempts, malware, and suspicious behaviors—its unprecedented growth also creates new challenges.
AI can be weaponized by malicious actors to launch more sophisticated attacks. For example:
AI-powered phishing – Attackers use AI to generate hyper-personalized emails that mimic real conversations, making phishing scams harder to detect.
Deepfake emails and voice spoofing – AI can create fake emails or audio clips that impersonate executives, tricking employees into sharing sensitive data or transferring funds.
Automated malware delivery – AI helps generate new malware that evades security filters and adapts to exploit system vulnerabilities.
This makes it essential for businesses to implement AI-driven email security systems that can adapt to evolving threats.
Ethical AI in email systems
As AI becomes more integral to email security, IT leaders need to ensure it’s implemented ethically and responsibly. Ethical AI refers to the use of AI technologies in ways that are transparent, unbiased, and accountable. In the context of email security, ethical AI means developing systems that don’t inadvertently expose sensitive information or violate privacy rights.
For IT professionals, the challenge lies in balancing AI’s potential for enhancing security with the need to uphold ethical standards.
Key considerations include:
Bias reduction: AI systems must be trained to avoid discriminatory practices or decisions based on data bias. This is especially important when filtering or identifying legitimate communications.
Transparency: Email security AI systems must offer clear explanations of how they assess risks, make decisions, and flag potential threats. This is so users trust their findings.
Accountability: Any AI-driven security system should have mechanisms for tracking its decisions and providing explanations when things go wrong.
Increased scrutiny on data privacy
At the same time, the global regulatory landscape is having to change to keep pace with technological change. Legislation like the General Data Protection Regulation (GDPR) and emerging regulations such as the EU AI Act mandate strict data protection practices. These regulations mandate businesses strengthen their email security practices to protect sensitive data, ensure compliance, and avoid hefty fines. Non-compliance can lead to financial penalties and significant damage to a company’s reputation and brand trust.
This intersection between AI innovation and regulatory requirements is pushing IT leaders to integrate advanced security features. These are designed to protect data from both internal and external threats, while meeting the standards of emerging laws.
Adapting email security strategies
The regulatory environment around email and data security is becoming increasingly complex. As regulations evolve, businesses must continuously adjust their email security strategies to ensure they remain compliant.
Data protection mandates: Increasing regulations are driving companies to adopt more rigorous data protection practices. These include ensuring that personal data is stored and transmitted securely, which is critical when handling email communications containing sensitive information. Organizations must implement end-to-end encryption, enforce strong access controls, and regularly audit their email systems for vulnerabilities.
Compliance-driven security measures: Regulations often require specific actions from businesses to protect email systems. These include implementing multi-factor authentication (MFA) for accessing email accounts and using secure email gateways to filter out harmful content. Businesses that don’t adapt their email security strategies risk facing both legal issues and financial penalties. On the other hand, implementing advanced security practices ensures compliance while strengthening brand reputation by showing customers that their data is being handled responsibly and ethically.
Common risks in email security
Cybercriminals use email vulnerabilities to launch attacks on organizations, steal sensitive data, and compromise systems. For example, nearly 1.2% of all emails sent are malicious, accounting for 3.4 billion phishing emails daily.
Let's look at some of the other risks in email security:
1. Phishing, spoofing, and social engineering attacks
Phishing involves sending fraudulent emails designed to trick the recipient into revealing sensitive information. These could be login credentials, financial data, or personal details.
Phishing emails often appear to come from trusted sources, such as colleagues, business partners, or well-known brands. This makes them difficult to identify.
Spoofing is a form of phishing where the attacker falsifies the sender's address to appear as though the email’s coming from a legitimate source. This can lead to employees unwittingly sharing sensitive information.
Social engineering attacks use psychological manipulation to persuade recipients to take certain actions. These include clicking on malicious links or downloading harmful attachments. Attackers may impersonate a high-ranking executive or business partner to increase the chances of success.
2. Malware and ransomware delivered through email
Malware and ransomware attacks often begin with malicious email attachments or links. Once the user opens the attachment or clicks on the link, malware is installed on the system, potentially causing significant damage, such as data theft, system corruption, or complete system compromise.
Malware includes viruses, worms, and Trojan horses that can disrupt operations, steal sensitive information, or cause system failures.
Ransomware is a particularly dangerous type of malware that locks the user’s files or entire system, demanding payment (typically in cryptocurrency) in exchange for unlocking the files.
3. Employee-related risks from unsecured email signatures
While email signatures are an important part of professional communication, they can also be a potential security risk if not managed properly. Poorly designed and unsecured email signatures can be exploited by attackers to spoof or impersonate employees, creating a gateway for malicious activities.
Signature spoofing occurs when attackers add malicious links or misleading information to an email signature, impersonating a legitimate employee or department within the organization.
Lack of standardization can lead to inconsistent use of security protocols in signatures, such as missing email disclaimers or incorrect branding. This makes a company more susceptible to phishing attacks or brand damage.
4. Link and attachment-based threats
Links and attachments are common attack vectors. What might look like an innocent link or attachment can lead to a phishing site, download malicious software, or open the door to data theft.
Link-based threats often involve URL redirection. The attacker hides the actual destination URL by masking it with an innocuous-looking link. Once clicked, the link may lead the user to a fraudulent website designed to capture sensitive information or infect their system with malware.
Attachment-based threats are another common method for delivering malware, ransomware, or other harmful software. Attackers often use file types like .exe, .zip, .pdf, and .docx to disguise malicious content.
The key elements of email security
A great email security strategy involves a layered approach. Authentication protocols, encryption measures, secure email gateways, and email signature management need to work together to protect sensitive data and defend against evolving threats.
Let’s look at each of these elements in more detail:
1. Authentication protocols
Authentication protocols verify the legitimacy of email senders, while protecting recipients from phishing, spoofing, and other email-based attacks. Together, these protocols form a robust framework for preventing domain spoofing so that only legitimate emails reach recipients' inboxes:
SPF (Sender Policy Framework): SPF allows domain owners to specify which mail servers are authorized to send emails on behalf of their domain. By checking the sender’s IP address against the authorized list in the SPF record, receiving email servers can identify and block fraudulent emails from unauthorized senders.
DKIM (DomainKeys Identified Mail): DKIM adds a digital signature to outgoing emails. This signature is generated using the sender’s private key and can be verified by the recipient’s email server using the public key stored in the domain’s DNS records. This ensures the email has not been tampered with during transit and confirms the authenticity of the sender.
DMARC (Domain-based Message Authentication, Reporting, and Conformance): DMARC builds on SPF and DKIM by allowing domain owners to specify how email servers should handle unauthenticated messages (reject or quarantine them). DMARC also provides reporting mechanisms that help identify malicious activity and improve email security posture over time.
2. Encryption
Encryption plays a critical role in email security. It keeps sensitive information protected while it’s being sent between senders and recipients. By implementing encryption, businesses reduce the risk of data breaches. This means that even if emails are intercepted, their contents remain unreadable to unauthorized parties.
There are two main types of email encryption:
Transport Layer Security (TLS): TLS encrypts the connection between email servers, making it difficult for hackers to intercept or tamper with the email while it’s in transit. TLS is widely used in modern email systems to secure the communication channel, but it requires both the sender and recipient’s servers to support it.
End-to-end encryption: E2EE ensures that only the intended recipient can decrypt and read the contents of the email. Popular tools for E2EE include PGP (Pretty Good Privacy) and S/MIME (Secure/Multipurpose Internet Mail Extensions). This level of encryption is especially important for protecting highly sensitive data, such as personal identification information (PII) and financial records.
3. Secure email gateways
A Secure Email Gateway (SEG) filters incoming and outgoing emails for threats and malicious content. SEGs also operate as a barrier between the email server and the internet, screening all email traffic for potential risks before it reaches the inbox. By providing an additional layer of defense, they reduce the risk of email-based cyberattacks, so that only safe emails reach employees:
Phishing protection: SEGs use advanced algorithms and machine learning to identify phishing attempts based on suspicious links, content, and sender behaviors. They can block malicious emails that impersonate legitimate organizations or individuals, preventing attackers from gaining access to sensitive information.
Malware detection: SEGs scan email attachments and links for known malware signatures and malicious code. By preventing harmful files from reaching the recipient’s system, SEGs play a crucial role in defending against ransomware and other types of malware.
Spam filtering: SEGs also perform spam filtering so that inboxes remain free from unwanted and potentially harmful emails. Spam filters use predefined rules, blacklists, and some even use AI to detect and block unsolicited emails.
4. Email signature security
While often overlooked, email signatures play an integral part in email security. Malicious actors can exploit email signatures to add harmful links, promote phishing schemes, or even spread malware.
With human error contributing to 74% of security breaches, companies can’t afford to let end-users have control over editing their email signatures. By securing email signatures, organizations minimize the risk of using email signatures as an attack route, while maintaining brand consistency and protecting their reputation.
Email signature management: Implementing a centralized email signature management platform standardizes email signature templates across the organization. This means signatures won’t contain unauthorized or malicious links and will comply with corporate policies and branding guidelines. A professionally branded email signature also protects recipients by making it easier to spot illegitimate emails.
Data integrity: Email signature security involves protecting the underlying data and templates used to generate them. If an attacker gains access to the signature management platform, they could alter signatures to redirect recipients to phishing sites or malicious content. Strong authentication and encryption practices should be implemented to protect signature data.
5. Endpoint security
Endpoint security is all about protecting the devices that access email systems. Since these devices are often the entry points for cyberattacks, securing them is a critical part of a good email security strategy. Endpoint security focuses on preventing unauthorized access, so that devices can’t be easily compromised by malicious actors. By securing endpoints, organizations prevent malware, phishing attempts, and other threats from reaching email systems via devices that have access to sensitive corporate communication.
Antivirus software: Antivirus programs help protect endpoints from malware that may be delivered via email. By scanning incoming email attachments and links, these tools can prevent malicious files from being executed on the device.
Mobile Device Management (MDM): For organizations that support mobile email access, MDM solutions allow smartphones and tablets to access company email to stay compliant with security protocols. This includes enforcing encryption, securing email apps, and remotely wiping devices in case of loss or theft.
Behavioral analytics: Advanced endpoint security solutions use behavioral analytics to detect unusual activity on devices. For example, if a user suddenly opens an email attachment from an unknown sender or accesses a large volume of emails in a short time, the system can flag this as suspicious behavior and alert the IT team.
Patch management: Regularly updating software and operating systems closes security gaps that could be exploited by attackers. Endpoint security tools often include automated patch management to keep all devices up to date with the latest security fixes.
6. Email security software
Email security software is designed to safeguard both inbound and outbound emails from various cyber threats. These are an essential component of any email security strategy, offering a range of features to protect users and organizations from email-based attacks.
Anti-phishing software: Anti-phishing tools use machine learning and heuristic analysis to detect phishing emails and block them before they reach users’ inboxes. These analyze email content, sender information, and URLs to identify suspicious or fraudulent messages.
Spam filters: Spam filters are a core feature of most email security software. They scan incoming emails for common characteristics of spam, such as unsolicited commercial messages or suspicious attachments. These emails are then moved to the spam folder or blocked entirely.
Malware and ransomware detection: Email security software often includes malware scanning capabilities that detect malicious attachments or links embedded in emails. Ransomware protection is particularly important, as these types of attacks are commonly delivered via email attachments.
Data Loss Prevention (DLP): DLP tools within email security software help prevent sensitive data from being sent outside the organization without authorization. These tools can scan emails for personal identification information (PII), financial data, and other confidential information, and block or encrypt them if necessary.
Email archiving: Many email security solutions include archiving features that allow organizations to securely store email communications. This ensures that email data is protected from loss or tampering, while also supporting compliance and regulatory requirements.
The most popular email security software is designed to work with enterprise email systems such as Microsoft 365 (Office 365) and Google Workspace for comprehensive protection.
Best practices for email security
Maintaining strong email security is an ongoing process that involves both technology and training. By following industry best practices, businesses reduce the risk of email-related threats. Below are the key practices for strengthening email security across the organization.
1. Employee training
Employees are the first line of defense against email security threats. Cybercriminals often rely on human error to launch successful attacks, such as clicking on a phishing link or downloading a malicious attachment.
By regularly training employees on how to recognize potential threats and follow safe email practices, businesses reduce their vulnerability.
Phishing simulations: Conduct simulated phishing campaigns to educate employees on how to spot fraudulent emails and suspicious links. This hands-on training helps reinforce security awareness in a real-world context.
Security policies and protocols: Establish clear guidelines on what employees should do if they receive a suspicious email. This includes reporting it to the IT department, not clicking on suspicious links, or downloading attachments from unknown sources.
Ongoing training: As cyber threats evolve, so should employee training. Regular updates and refreshers on emerging risks keep employees vigilant.
2. Consider cloud-based security solutions
As more organizations move to cloud-based email solutions, securing emails within these environments has become a top priority. Cloud-based email systems such as Microsoft 365 (Office 365) are vulnerable to the same threats as on-premises email systems like Microsoft Exchange, but require specialized tools and approaches to secure them effectively.
As email systems continue to move to the cloud, it’s critical for organizations to adopt a layered approach to security. They should combine cloud-native tools with third-party email security solutions to ensure comprehensive protection.
Cloud email gateways: Cloud email gateways act as intermediaries between users and cloud email services. They scan all inbound and outbound emails for threats before they reach the email server. These solutions provide an additional layer of security, protecting users from phishing, malware, and other email-borne attacks. Providers like Proofpoint Essentials and Mimecast Cloud Email Security offer cloud-specific email filtering and threat detection capabilities.
Advanced threat protection (ATP): Microsoft 365 and other cloud email platforms offer built-in Advanced Threat Protection (ATP) services that detect and block sophisticated attacks like zero-day exploits, ransomware, and phishing attempts. ATP features often include real-time scanning of attachments, URL filtering, and machine learning-based threat analysis.
Data encryption and loss prevention: Cloud-based email security solutions provide data encryption capabilities to protect sensitive information sent via email. This is especially important for compliance with regulations such as GDPR and HIPPA, which require sensitive data to be securely encrypted during transmission. Additionally, DLP features can be used to prevent data leakage by scanning outgoing emails for sensitive content before they’re sent.
Identity and access management (IAM): Managing user access and ensuring that only authorized individuals can access email accounts is crucial for preventing unauthorized access and ensuring that email communications are secure. Cloud-based IAM solutions offer features like MFA and role-based access controls (RBAC) to improve email security.
Backup: Cloud-based email backup solutions protect email data from loss, corruption, or accidental deletion. These also help organizations comply with industry regulations that require email retention for specified periods.
3. Regular updates
Regular software updates and patches ensure that email systems remain secure. Cybercriminals are quick to exploit known vulnerabilities in outdated systems, so it’s essential to keep email servers and client software up to date.
Enabling automatic updates for email systems and security software helps ensure that security patches are applied as soon as they’re released, minimizing the window of vulnerability. They also reduce the risk of attacks targeting known weaknesses and ensure that the organization remains protected.
| Best practices for email signature security | 5 ways unsecured signatures put employees at risk |
| Email compliance checklist for IT | The impact of email security on brand trust |
Solutions for stronger email security
Securing email communications requires the right tools and solutions. A variety of email security software and apps can protect inboxes from cyber threats, ensure regulatory compliance, and safeguard sensitive data. Below are some of the most effective email security solutions that organizations can use to strengthen their defenses.
Learn more about the top IT security tools by checking out our article on The Top 8 IT Security Tools for Brand Protection.
1. Email security software options
The best email security solutions offer multi-layered protection that encompasses various features. These include real-time threat detection, advanced filtering, and comprehensive reporting.
Popular email security software options include:
Proofpoint: Known for its strong protection against phishing and advanced malware, Proofpoint also offers data encryption and compliance tools.
Barracuda: Offers an easy solution with cloud-based filtering and real-time protection against threats like phishing and ransomware.
Mimecast: This software protects against phishing, malware, and impersonation attacks, while also offering secure email archiving and compliance tools.
2. Other tools for workplace protection
In addition to traditional email security software, several apps and tools can be integrated with popular email platforms for added protection. By using these, IT teams further reduce the risk of email-related security breaches and enhance their organization’s ability to detect and respond to threats.
Some useful email security apps and tools include:
Exclaimer: A secure email signature management solution that keeps email signatures compliant, secure, and aligned with organizational branding. Reliability and Security within Exclaimer highlights how this solution integrates security best practices and compliance features.
Vade Secure: A predictive email defense tool that provides real-time filtering and detection of malicious emails before they reach your inbox.
Tessian: Uses machine learning to prevent data breaches and mitigate risks by automatically detecting and stopping harmful emails, including those that contain sensitive information.
Pro tip: Don't overlook the importance of email signatures when it comes to securing your company's emails.
Email security for compliance
Email security isn’t only about protecting against cyber threats—it's also about ensuring your organization meets the required legal and regulatory standards. Compliance frameworks such as GDPR, HIPAA, and others have specific requirements regarding data protection, including how sensitive information is transmitted via email.
It’s essential for organizations to implement email security practices that align with these regulations to avoid legal penalties and maintain customer trust.
Key compliance frameworks
General Data Protection Regulation (GDPR): The GDPR, which governs data protection and privacy in the European Union and European Economic Area, has specific provisions about email security. Organizations must protect personal data sent via email from unauthorized access and breaches. Email security measures, such as encryption, strong authentication, and secure email gateways, are essential for complying with GDPR requirements.
Health Insurance Portability and Accountability Act (HIPPA): HIPAA mandates U.S. healthcare providers, insurers, and business associates ensure the confidentiality, integrity, and security of protected health information (PHI). Email is often used to transmit PHI, making email security vital for compliance. Encryption, secure communication channels, and secure email signature practices are necessary to ensure that PHI remains protected under HIPAA.
California Consumer Privacy Act (CCPA): Like GDPR, CCPA requires businesses in California protect consumers' personal data, with email security playing a significant role. Securing email communications involving personal data helps businesses avoid penalties and safeguard customer trust.
Sarbanes-Oxley Act (SOX): For publicly traded companies, SOX requires certain controls and practices around data retention and transmission. Email security is a key element of compliance with SOX, as emails may contain sensitive financial data that needs to be secure, archived, and monitored.
Payment Card Industry Data Security Standard (PCI DSS): If your business handles payment card data, PCI DSS requires that email communications involving this information are encrypted. Email security measures that address encryption and data loss prevention (DLP) are necessary for PCI DSS compliance. Read more in our playbook for data security success.
How to assess your email security
Protecting your organization’s sensitive data starts with strong email security. By assessing your current email system, you’ll identify any vulnerabilities and take proactive measures. This will strengthen your cyber defenses and safeguard against evolving threats.
Checklist for assessing your email security effectiveness
✔ Check for basic security features
Does your email system have these fundamental security features in place?
✔ Evaluate endpoint security
Are the devices accessing your email protected with the following?
✔ Assess Data Loss Prevention (DLP) tools
Does your organization have data loss prevention measures in place to prevent accidental or malicious sharing of sensitive information through email?
✔ Test for vulnerabilities
Do you conduct regular security audits and penetration testing to identify weaknesses in your email security system?
✔ Review user access and privileges
Do you regularly review user access rights to your email system, including email signatures?
✔ Monitor for suspicious activity
Do you undertake these best practices for suspicious activity?
Next steps for implementing an email security strategy
Adopt advanced email security tools
Establish clear email security policies
Monitor and adapt to emerging threats
Conclusion: Strengthening your email security
Email security is a cornerstone of both IT infrastructure and brand trust in the business world. As cyber threats become more sophisticated, keeping your organization's email system secure protects sensitive data and safeguards your brand's reputation.
By using robust email security measures, you can effectively mitigate risks like phishing, malware, and unauthorized access. This ultimately means your organization’s communications stay trustworthy and protected.
Using Exclaimer to support email security
Exclaimer’s email signature management solution improves overall email security by centralizing control over signatures.
Here’s how it reduces the risk of unauthorized modifications or tampering:
✔ Centralized control
Ensures all email signatures are standardized and securely managed, reducing the risk of unauthorized changes.
✔ Protection against spoofing and phishing
Consistent, company-approved signatures make it easier for employees and customers to spot fraudulent emails and prevent impersonation attacks.
✔ Role-based access controls
Limits signature editing to authorized personnel, reducing human error and security risks.
✔ Secure cloud infrastructure
Ensures compliance with security best practices, protecting sensitive data while maintaining efficiency. System updates are automatically applied, leaving companies less vulnerable to security risks compared to on-premises software.
Secure your email signatures with Exclaimer. Start your free trial today!
[Webinar] Shield your inbox: How to master email security
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